Electrolyte for electrolytic condensers



Patented Sept. 16, 1941 ELECTROLYTE FOR ELECTROLYTIC CONDENSERS SamuelRuben, New Rochelle, N. Y.

No Drawing. Application July 8, 1939, Serial No. 283,453

9 Claims.

This invention relates to electrolytes for electrolytic condeners of thedry electrolytic type.

The application is a continuation in part of my copending applicationsSerial No. 10,288, filed March 9, 1935 for Electrolytic condenser, nowPatent No. 2,166,180, and Serial No. 11,076, filed March 14, 1935 forFilm maintaining electrolyte, now Patent No. 2,166,179.

The above mentioned applications describe electrolytic condensers inwhich the electrolytes comprise conductive film-forming shellac or rosincompositions. For a more detailed description of the electrolytes andtheir uses, reference may be had to said applications and to the patentsabout to issue thereon.

The present invention is distinguished from my prior two inventions bythe use of a conductive film-forming hydrogenated tree resinelectrolyte. The partial or complete substitution of the hydrogenatedtree resin for the rosin or shellac provides an electrolyte which ismore resistant to heat and to oxidation and is more stable than theelectrolytes of my prior appplications. In addition the improvedhydrogenated tree resin electrolyte possesses a high degree of fluidity,which property facilitates the impregnation of wound condenser sections.

The electrolytes may be made by several formulas as follows:

(a) 28 grams of sodium hydroxide are dissolved in 800 c. c. of boilingwater; 200 grams of hydrogenated rosin are added and the mixture held atboiling until all of the hydrogenated rosin is dissolved; 90 c. c. ofethylene glycol are added and the temperature raised to 120 C. at whichpoint 100 grams of borax are added and dissolved into the boilingcomposition to form the complete electrolyte.

(b) 23 grams of sodium hydroxide are dis solved in 500 c. c. of boilingwater; 200 grams of hydrogenated rosin are added, the solution beingkept at boiling and when the hydrogenated rosin is dissolved, 40 c. c.of ethylene glycol are added and the composition heated to 120 C.

(c) 200 grams of hydrogenated rosin and 500 c. c. of water are heated toboiling at which point 50 c. c. of ammonia (28% solution) are slowlyadded, the mixture being kept at the boiling point. 100 c. c. ofethylene glycol are added and the composition heated to 120 C.

(d) 28 grams of sodium hydroxide are dissolved in 800 c. c. of boilingwater; 100 grams of hydrogenater rosin and 100 grams of shellac areadded and the mixture held at boiling until the shellac and hydrogenatedrosin are dissolved;

c. c. of ethylene glycol are added and the temperature raised to 120 C.at which point grams of borax are added and dissolved into the boilingcomposition to form the complete electrolyte.

While it is possible to react the constituents of the electrolytewithout water I prefer to first form the aqueous solution as set forthand thereafter drive ofi the water by heating. No free water is presentin the completed electrolyte.

In the above formulas, I have found that potassium hydroxide can besatisfactorily substituted for the sodium hydroxide and that thecarbonates of potassium and sodium may be substituted for the hydroxide,although not as satisfactorily, as a longer time is required for thereaction and a considerable amount of carbon dioxide is evolved.

Ethylene glycol is the preferred plasticizer in the above formulas,although glycerine or triethenolamine may also be used, separately or incombination with the glycol. Where the hydrogenated rosin is firstreacted with the sodium hydroxide or other alkali, glycol or glycerolborate may be use das a plasticizer.

Triethanolamine, being somewhat alkaline, may, for electrolytes ofcertain types, serve the combined function of an alkaline neutralizerfor the acidic resin and plasticizer. In such cases the electrolytewould be composed merely of the resin and triethenolamine reactedtogether.

Dependent upon the temperature to which the electrolyte mixture isbrought during its preparation, the resistance per cm. may be variedover wide limits, as from 1500 ohms to 50,000 ohms, the particularservice to which the condenser is to be applied being perhaps the mostdetermining factor. Under conditions where a high operating temperatureis to be encountered a high initial resistance is desirable. This highinitial resistance as well as the power factor, drops asthe condenserreaches ts equilibrium operating temperature. When lower operatingtemperatures are to be encountered, initially low resistanceelectrolytes may be used with improved condenser power factor.

When properly prepared, the electrolyte is very viscous, plastic,varnish-like material and remains indefinitely in this condition, eventhough exposed to the atmosphere. Its consistency may be varied, ofcourse, depending upon the proportions of ingredients and method ofpreparation particularly with respect to the temperature to which thecomposition is heated during its preparation. The electrolyte may bemade in the-form of a-viscous liquid, which will slowly drip, or it maybe made sufliciently immobile so that it will adhere to the electrodeswithout dripping or flowing. Preferably it may resemble a non-dryingapplied varnish. The immobility of the electrolyte serves to minimizethe efiect of any impurities which may be present in the resins. Theelectrolyte is preferably applied hot in the form of a tacky,electrically conductive film maining composition, which sticks to thecurrent blocking film and tends to protect and maintain the film.

If desired the fluidity of the electrolyte may be increased by theaddition of glycol or other suitable material; or it may be decreased byreducing the amount of glycol.

What is claimed is: v

1. An electrolyte for electrolytic condensers, comprising the reactionproduct of hydrogenated .rosin, an alkali and a plasticizer.

3. An electrolyte for electrolytic condensers composition and aplasticizer therefor.

4. An electrolyte for electrolytic condensers comprising the reactionproduct of hydrogenated rosin, shellac, an alkali and a plasticizer.

5. An electrolyte for electrolytic condensers comprising the reactionproduct of hydrogenated rosin, an alkali and glycol.

6. An oxide film maintaining electrolyte comprising the reaction productof hydrogenated rosin, shellac, sodium borate and ethylene glycol.

'7. An oxide film maintaining electrolyte comprising the reactionproduct of hydrogenated rosin, a borate and a plasticizer.

8. An oxide film-maintaining electrolyte for electrolytic condenserscomprising the reaction product of hydrogenated tree resin with analkaline neutralizer for the acidic constituents of said resin and aplasticizer therefor.

9. An oxide film-maintaining electrolyte for electrolytic condenserscomprising the reaction product of hydrogenated rosin with an alkalineneutralizer for the acidic constituents of said resin and a plasticizertherefor.

SAMUEL RUBEN.

